Roasting apparatus for roasting fresh or green coffee beans is well-known and in wide use. The taste and fragrance of coffee depend largely on how and the degree to which the coffee beans have been roasted and how quickly, following roasting, the beans are consumed by brewing coffee with them. It is desirable to produce roasted coffee beans that are consistent in taste and fragrance and in a manner that minimizes storage times to optimize the taste of fresh coffee.
In the past, coffee beans were usually roasted at a central plant for sale at multiple retail locations, such as supermarkets, stores and specialty shops, as well as coffee and espresso bars. The roasted beans must be stored and shipped before they reach the consumer. This is in and of itself time-consuming and costly. In addition, for cost and transportation reasons it is not feasible to effectively distribute coffee that is roasted on a given day for sale at the various retail establishments on the same day. Thus, coffee beans presently for sale at retail establishments are seldom fresh and, typically, they are several days to several weeks old before they reach the consumer. This compromises the quality, and especially the aroma, of the coffee and, additionally, increases its cost because of the need to make relatively many deliveries from the roasting plant to the retail locations.
Such roasting techniques had additional problems. At typical roasting temperatures of about 500° F. (about 260° C.), large amounts of smoke and other byproducts are generated, such as carbon monoxide, white plume smoke, hydrocarbons, and volatile organic compounds (“VOCs”), that pollute the atmosphere unless the exhaust from the roaster is first cleaned. This typically required an expensive and energy-consuming afterburner that is normally built into the exhaust gas stack for the roasting machine extending through the surrounding wall or ceiling so that the vented exhaust is reasonably clean and non-polluting although it still contains air contaminants.
More recently, a roasting method and apparatus were developed that could be used at individual roasted coffee bean retail locations such as supermarkets, coffee shops and the like. Such roasters are described in International Application WO 99/23888. They cleaned the hot air used for roasting and cooled it to about room temperature so that the air could be discharged into interior locations, e.g. the interior of a store, without causing indoor pollution or undue heating. They required no exhaust to be discharged to the outside of the building, required no afterburners to eliminate pollutants, and roasted the coffee beans automatically without requiring the supervision of an experienced roastmaster. These roasters could economically roast relatively small batches of green coffee beans, for example the anticipated daily requirement so that truly fresh, daily roasted coffee could be sold.
In accordance with WO 99/23888, the roasting of beans for consumption (e.g. retail sale in stores or the brewing of coffee in espresso shops and the like) was conducted on site, for example in a store or an espresso shop, with individual, self-contained coffee roasting machines. Each such roasting machine was networked with a computer at a central control station that had the necessary processors and memory to record and store the roasting profiles/recipes and parameters needed for controlling and terminating the bean roasting.
For roasting coffee beans in the manner described in the preceding paragraphs, self-contained roasting machines were installed, for example, inside a retail establishment without a vent or exhaust to the exterior of the room. An air circulation system of such machines flowed heated intake air over the beans in the roasting chamber which exited the machine as used, contaminated exhaust air that included particulates, smoke and other pollutants. An air cleaning arrangement located downstream of the container effectively removed all contaminants entrained in the exhaust air to render it substantially pollutant-free used air. An air cooling arrangement was further operatively coupled with the air circulation system for cooling the used air so that it could be released into a surrounding room, e.g. a supermarket.
Thus, the exhaust air from the roaster was filtered to remove therefrom substantially all particulate matter down to sub-micron range, e.g. down to a size as small as about 0.03 micron, with a high up to 99.97% removed efficiency, and before the used air was discharged into the surrounding store it was cooled—according to WO 99/23888—to a temperature of no more than about 115° F. (about 46° C.) and preferably no more than about 100° F. (about 38° C.). In practice, the used air released by roasting machines constructed in accordance with WO 99/23888 had a temperature of no less than about 175° F. to 190° F. When the filtered and cooled air was discharged, there was no detectable pollution and at most only a negligible heating of air inside the store.